• Support PF! Buy your school textbooks, materials and every day products Here!

Help with Stoichiometry

  • #1
a. A sample of CaCO3 decomposes when heated to form calcium oxide and carbon dioxide. 1.5432 g of CO2 are released in the reaction. Find g of CaCO3 in the original sample.
CaCO3 --> CO2 + CaO

1.5432 g CO2*(1 mol of CO2/44.01 g) = 0.035065 mol of CO2*(1 mol CaCO3/1 mol CO2) = 0.035065 mol CaCO3

0.035065 mol CaCO3*(100.09 g/ 1mol CaCO3) = 3.5097 g CaCO3??


b. The original sample was a mixture from which only CaCO3 released carbon dioxide. Calculate the percentage by mass of CaCO3 if original's sample mass was 5.768 g.


Do I divide 3.5097 g CaCO3/5.768 g * 100 or must I subtract the grams of CO2 from the original sample's mass?

Thanks.
 
Last edited:

Answers and Replies

  • #2
Any volunteers?

Thanks again.
 
  • #3
Gokul43201
Staff Emeritus
Science Advisor
Gold Member
7,051
16
Soaring Crane said:
a. A sample of CaCO3 decomposes when heated to form calcium oxide and carbon dioxide. 1.5432 g of CO2 are released in the reaction. Find g of CaCO3 in the original sample.
CaCO3 --> CO2 + CaO

1.5432 g CO2*(1 mol of CO2/44.01 g) = 0.035065 mol of CO2*(1 mol CaCO3/1 mol CO2) = 0.035065 mol CaCO3

0.035065 mol CaCO3*(100.09 g/ 1mol CaCO3) = 3.5097 g CaCO3??
That's correct.


b. The original sample was a mixture from which only CaCO3 released carbon dioxide. Calculate the percentage by mass of CaCO3 if original's sample mass was 5.768 g.


Do I divide 3.5097 g CaCO3/5.768 g * 100 or must I subtract the grams of CO2 from the original sample's mass?

Thanks.
This looks a little silly, but your first idea seems right.
 
  • #4
33
0
all seemed right: (3.5097/5.768)*100 should do it.
 

Related Threads for: Help with Stoichiometry

  • Last Post
Replies
4
Views
3K
Replies
1
Views
8K
  • Last Post
Replies
1
Views
4K
  • Last Post
Replies
3
Views
4K
  • Last Post
Replies
5
Views
3K
  • Last Post
Replies
4
Views
6K
  • Last Post
Replies
3
Views
3K
  • Last Post
Replies
1
Views
1K
Top